Fig. 1. Configuration of the Tm³⁺-doped fiber random laser based on grating feedback technology

Fig. 2. Transmission spectrum of the high-reflectivity fiber Bragg grating

Fig. 3. Output spectra of the Tm³⁺-doped fiber random laser with pump powers near the threshold

Fig. 4. Random laser output spectra measured at different pump powers

Fig. 5. Output characteristics of Tm³⁺ -doped fiber random laser

Fig. 6. Laser output spectra of multiple measurements at pump power of 3.8 W

Fig. 7. Output power of the random laser versus time